Supported PCD/PCBN tool with arched intermediate layer

Abstract

A new PCD/PCBN tool and method for making the same involve the use of an intermediate layer of polycrystalline material between a substrate and an outer working layer. The intermediate layer is formulated to limit or prevent the amount of cobalt or other binders which may infiltrate the outer working layer and accelerate deterioration under high throughput conditions. In accordance with one aspect of the invention, the substrate is corrugate or rounded projections to both reduce stress and to decrease infiltration of cobalt through the polycrystalline structures. In accordance with another aspect of the invention, the bonding medium and/or binder agents in the intermediate layer may be selected to decrease mobility of cobalt and the like.

What is claimed is: 
     
       1. A new supported polycrystalline compact, the compact comprising: a substrate configured for receiving a polycrystalline element, the substrate having a plurality of projections;   an intermediate layer having a plurality of super hard crystals bonded together, and bonding medium therefor, the super hard crystals being at least 50 percent by volume of the intermediate layer, the intermediate layer being configured for nesting between the projections of the substrate and being bonded thereto; and   a polycrystalline outer layer bonded to the intermediate layer, said outer polycrystalline layer being isolated from the projections of the substrate by the intermediate layer.   
     
     
       2. The supported compact of claim 1, wherein the bonding medium comprises at least one of the group consisting of a carbide, nitride, a carbonitride of the IVb, Vb, VIb transition metals. 
     
     
       3. The supported compact of claim 1, wherein the outer layer and the intermediate layer each include plurality of crystals and bonding medium for holding the crystals together, and wherein the intermediate layer has a higher concentration of bonding medium than the outer layer. 
     
     
       4. The supported compact of claim 3, wherein the intermediate layer's content of bonding medium is at least 30% by volume. 
     
     
       5. The supported compact of claim 1, wherein said super hard crystals of the intermediate layer further comprises a fine grade polycrystalline material having a pre-bonding average particle size of about 0.5 to about 20 μm. 
     
     
       6. The supported compact of claim 1, wherein said intermediate layer further comprises a binding agent. 
     
     
       7. The supported compact of claim 6, wherein said binding agent further comprises at least one of the group consisting of group VIII metals. 
     
     
       8. The supported compact of claim 7, wherein said binding agent is a member selected from the group consisting of cobalt, nickel, and iron.